elements Form Compounds, chemistry homework help

QUESTION 1

If you know the number of moles in a sample of a substance, which of the following do you also know about that sample?

the mass of that sample

the volume of that sample

the number of representative particles in that sample

the coefficient of the substance when in a chemical reaction

3 points Save Answer

QUESTION 2

Which contains a greater number of atoms, a mole of silver or a mole of gold?

A mole of silver.

A mole of gold.

They both contain the same number of atoms.

The answer cannot be determined without knowing the molar mass of each element.

3 points Save Answer

QUESTION 3

How many atoms are in 0.788 moles of sodium hydroxide?

1.42 x 1024 atoms

7.60 x 1023 atoms

4.70 x 1023 atoms

2.36 x 1023 atoms

3 points Save Answer

QUESTION 4

How many atoms are in 0.654 moles of lithium chloride?

3.93 x 1023 atoms

7.87 x 1023 atoms

9.20 x 1023 atoms

1.18 x 1024 atoms

3 points Save Answer

QUESTION 5

Determine the molar mass of Ca(OH)2.

29.0 g/mol

38.0 g/mol

57.1 g/mol

74.1 g/mol

3 points Save Answer

QUESTION 6

Which of the following is the molar mass of NaCl?

28.00 g/mol

58.44 g/mol

811.8 g/mol

3.500 x 1025 g/mol

3 points Save Answer

QUESTION 7

If you are given the number of particles in a substance sample, what is the first step you should take to determine how many grams are present in that sample?

find the molar mass of the substance

convert the grams to particles

convert the moles to mass

convert the number of particles to moles

3 points Save Answer

QUESTION 8

If you are given the mass of a substance sample in grams, what is the first step you should take to determine how many representative particles are in that sample?

find the molar mass of the substance

convert the grams to particles

convert the mass to moles

convert the moles to particles

3 points Save Answer

QUESTION 9

Percent composition identifies the amount (in percent) of each element present in a compound.

TRUE

FALSE

2 points Save Answer

QUESTION 10

The percent composition of acetic acid, HC2H3O2, is:

20% carbon, 2% hydrogen, 27% oxygen

40% carbon, 7% hydrogen, 53% oxygen

23% carbon, 7% hydrogen, 70% oxygen

Cannot be determined from the information given

3 points Save Answer

QUESTION 11

One way to determine the empirical formula of a compound involves using the percent composition of the compound.

TRUE

FALSE

2 points Save Answer

QUESTION 12

A compound was analyzed and found to contain only 14 grams of calcium, 11 grams of oxygen and roughly 0.7 grams of hydrogen. What is the empirical formula of the compound?

Ca2OH

CaOH

CaO2H

Ca(OH)2

3 points Save Answer

QUESTION 13

It is possible to determine the molecular formula without the empirical formula.

TRUE

FALSE

2 points Save Answer

QUESTION 14

Phosphoric acid, which is a component of many soft drinks, has a molar mass of 98.00 grams per mole. A sample of phosphoric acid contains 3.1 percent hydrogen, 31.6 percent phosphorus, and 65.3 percent oxygen by mass. What is the molecular formula of phosphoric acid?

HPO

H2PO2

H3PO4

H6P2O8

3 points Save Answer

QUESTION 15

In the equation, 2H2 + O2 Imported Asset 2H2O, which substance(s) are the reactant(s)?

H2

O2

H2O

H2 and O2

3 points Save Answer

QUESTION 16

Which of the following data does a complete and balanced chemical equation NOT reveal?

the molar ratios of each of the reactants and products

the states of matter for each reactant and product

the correctly written formula for each reactant and product

the mass of each reactant and product

3 points Save Answer

QUESTION 17

If a reactant or product is part of a water solution, then (aq) is placed as a subscript after the chemical symbol for the substance.

TRUE

FALSE

2 points Save Answer

QUESTION 18

Select the properly written and balanced equation for the following chemical reaction: Solid iron (II) sulfide reacts with an aqueous solution of hydrochloric acid to produce hydrogen sulfide gas and solid iron (II) chloride.

FeS2 (s)+ 2HCl (aq) Imported Asset 2HS (g) + FeCl2 (s)

Fe2S2 (s) + 2HCL(aq) Imported Asset 2HS(g) + Fe2Cl2 (s)

FeS (s) + 2HCl (aq) Imported Asset H2S (g) + FeCl2 (s)

Fe2S (s) + HCl (aq) Imported Asset HS (g) + Fe2Cl

3 points Save Answer

QUESTION 19

Select the properly written and balanced equation for the following chemical reaction: Sodium metal and an aqueous solution of magnesium iodide react to produce an aqueous solution of sodium iodide and magnesium metal.

Na(s) + MgI (aq) Imported Asset NaI (aq) + Mg(s)

Na(s) + MgI2 (aq) Imported Asset NaI2 (aq) + Mg (s)

2Na (s) + MgI2 (aq) Imported Asset 2NaI (aq) + Mg (s)

2Na (s) + 4MgI (aq) Imported Asset 2NaI2 (aq) + 4Mg(s)

3 points Save Answer

QUESTION 20

Write the proper word equation to express the following chemical reaction: 4Fe (s) + 3Sn(NO3)4 (aq) Imported Asset 4Fe(NO3)3 (aq) + 3Sn (s).

Press Tab to enter the content editor. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac).

Path: pWords:0

5 points Save Answer

QUESTION 21

What type of reaction is represented by the following chemical equation? CH4 + 2O2 Imported Asset CO2 + 2H2O + heat/light

double replacement

single replacement

combustion

decomposition

3 points Save Answer

QUESTION 22

Which of the following reactions shows a double replacement reaction for CaBr2 reacting with Na2S?

CaBr2 + 2Na2S Imported Asset 2NaSBr + Ca

CaBr2 + O2 + Na2S Imported Asset CaO2 + 2NaBr + H2S

CaBr2 + Na2S Imported Asset 2NaBr + CaS

CaBr2 + Na2S Imported Asset 2CaSBr +2Na

3 points Save Answer

QUESTION 23

Which type of reaction is described by the following equation? 2LiCl + MgO Imported Asset Li2O + MgCl2. Explain your reasoning.

Press Tab to enter the content editor. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac).

Path: pWords:0

5 points Save Answer

QUESTION 24

Which law requires the balancing a chemical equation?

Conservation of molecules

Conservation of energy

Conservation of mass

Conservation of elements

3 points Save Answer

QUESTION 25

Determine the atom inventory for the following equation: 2Na2O Imported Asset 4Na + O2. Does this equation follow the law of conservation of mass?

Na = 2, O = 1; Na = 4, O = 1; no, this equation does not follow the law of conservation of mass

Na = 4, O = 2; Na = 4, O = 2; yes, this equation does follow the law of conservation of mass

Na = 4, O = 4; Na = 4, O = 2; yes, this equation does follow the law of conservation of mass

Na = 2, O = 2; Na = 4, O = 2; no, this equation does not follow the law of conservation of mass

3 points Save Answer

QUESTION 26

In the reaction Fe2O3 + 3CO Imported Asset 2Fe + 3CO2, 10 moles of solid iron and 15 moles of carbon dioxide are produced from 5 moles of iron (III) oxide and 15 moles of carbon monoxide (CO). What is the mole ratio of carbon monoxide to solid iron?

15:10

5:10

3:2

2:1

3 points Save Answer

QUESTION 27

Choose the correct coefficients to balance the following equation: __Zn + __HCl Imported Asset __ZnCl2 + __H2.

1, 2, 2, 2

1, 2, 1, 1

2, 4, 2, 2

0, 2, 0, 0

3 points Save Answer

QUESTION 28

Choose the correct coefficients to balance the following equation: __CaCO3 + __HCl Imported Asset __CaCl2 + __CO2 + __H2O.

1, 2, 1, 1, 1

2, 4, 2, 1, 1

2, 2, 1, 2, 1

1, 2, 1, 1, 2

3 points Save Answer

QUESTION 29

The chemical reaction between aluminum and chlorine produces aluminum chloride:Al (s) + Cl2 (g) Imported Asset AlCl3 (s). 3.0 moles of solid aluminum would be required to react with 3.0 moles of chlorine gas.

TRUE

FALSE

2 points Save Answer

QUESTION 30

What is the mole ratio of oxygen to water in the following equation?C3H8 + 5O2 Imported Asset 3CO2 + 4H2O

10:8

10:9

5:4

7:7

3 points Save Answer

QUESTION 31

If 5.50 moles of calcium carbide (CaC2) react with an excess of water, how many moles of acetylene (C2H2) will be produced? The balanced equation for this reaction is CaC2 + 2H2O Imported Asset Ca(OH)2 + C2H2.

0.0800 moles

5.50 moles

11.0 moles

143 moles

3 points Save Answer

QUESTION 32

According to the following balanced chemical reaction, CsF(s) + XeF6(s)2 Imported Asset CsXeF7(s), 12.5 moles of CsF are reacted with 10.0 moles of XeF6. How many moles of the product will be produced?

10.0 moles

12.5 moles

3.97 x 103 moles

4.96 x 103 moles

3 points Save Answer

QUESTION 33

One method to produce nitrogen in the lab is to react ammonia with copper (II) oxide: NH3(g) + CuO(s) Imported Asset Cu(s) + H2O(l) + N2(g). After using 40.0 grams of NH3, 15.5 grams of N2 are produced. What is the percent yield of nitrogen in the reaction?

 
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